Sept.
23, 2008: In a briefing today at NASA headquarters,
solar physicists announced that the solar wind is losing power.
"The
average pressure of the solar wind has dropped more than 20%
since the mid-1990s," says Dave McComas of the Southwest
Research Institute in San Antonio, Texas. "This is the
weakest it's been since we began monitoring solar wind almost
50 years ago."
McComas
is principal investigator for the SWOOPS solar wind sensor
onboard the Ulysses spacecraft, which measured the decrease.
Ulysses, launched in 1990, circles the sun in a unique orbit
that carries it over both the sun's poles and equator, giving
Ulysses a global view of solar wind activity:
Above:
Global measurements of solar wind pressure by Ulysses. Green
curves trace the solar wind in 1992-1998, while blue curves
denote lower pressure winds in 2004-2008. [Larger
image]
The heliosphere.
Click
to view a larger image showing the rest of the bubble.
The
solar wind isn't inflating the heliosphere as much
clipped from: science.nasa.gov 
